The three aims of this project address the function of molecular asymmetries that occur very early in animal development, and the mechanisms by which they arise. Asymmetric cell division is essential for generation of cell-type diversity during differentiation and development. Failure o properly undergo asymmetric cell divisions can lead to defects in stem-cell renewal, tissue regeneration, and can contribute to carcinogenesis. We propose to use a near-ideal natural system, the early C. elegans embryo, to characterize the mechanisms of asymmetric distribution of cellular contents in specific blastomeres with modern genomic tools and analysis, followed by tests of function. Specifically, this proposal aims (1) to use blastomere-specific isolation, RNA- seq, and other high-throughput sequencing applications to comprehensively map RNA inheritance and transcriptional activity of seven invariant cell divisions in early C. elegans development, (2) to test the biological significance of asymmetric RNA segregation in development, and (3) to define the cis and trans-acting mechanisms required for asymmetric RNA segregation. To achieve these goals, we will also apply new approaches and technologies to the study of asymmetric segregation of cellular components. Our research plan is likely to identify cell-fate determinants and mechanisms that are generalizable to other systems, including humans.